Weight Symmetry and Latency Scores for Unexpected Surface Perturbations in Subjects With Traumatic and Vascular Unilateral Transtibial Amputation

Abstract

Background: Subjects with lower limb amputation develop new motor control strategies to preserve balance when they experience unexpected perturbations. Most studies performed thus far have not aimed to discuss the possible differences in postural control between subjects with vascular unilateral transtibial amputation (UTA) and subjects with traumatic UTA.

Objective: To analyze the automatic postural reaction in response to unexpected surface perturbations in a sample of subjects with traumatic and vascular UTA and to compare these observations with those for a group of healthy subjects.

Setting: University department.

Design: Observational study.

Participants: A total of 9 men with traumatic UTA, 7 men with vascular UTA, and 10 control subjects without amputation.

Intervention: Computerized dynamic posturography Smart EquiTest System version 8.0 was used to measure automatic postural responses in both groups.

Main outcome measures: The motor control test was used to assess the participants' automatic postural responses to unexpected surface perturbations.

Results: Latency scores showed that subjects with traumatic UTA coped with faster latencies under their sound limb than did the subjects with vascular UTA in medium backward and forward perturbations (medium-backward: P = .004; medium-forward: P = .037). In addition, the subjects with traumatic UTA also managed faster responses to medium-backward (P = .017 versus right control limb; P = .046 versus left control limb) and large-backward (P = .021 versus right control limb) and medium-forward (P = .012 versus right control limb; P = .043 versus left control limb) perturbations in their sound limb in contrast to control subjects. Weight symmetry showed that the subjects with traumatic UTA bore significantly more weight through their sound limb compared with the control subjects during medium and large backward translations (P = .028 and P = .045, respectively).

Conclusions: The subjects with traumatic UTA had a greater reliance on their sound limb, and they had faster latencies and more weight in the sound limb upon experiencing unexpected perturbations compared with the control subjects. Conversely, persons with vascular UTA experienced slower latency responses in the sound limb compared with persons with traumatic UTA.